Stability of Pt-Catalyzed Highly Oriented Pyrolytic Graphite Against Hydrogen Peroxide in Acid Solution

Aiming at clarifying the effects of hydrogen peroxide on the degradation of catalyst in polymer electrolyte fuel cells (PEFCs), a model electrode for the catalyst was prepared by electrodeposition of Pt on highly oriented pyrolytic graphite (HOPG) and its durability against hydrogen peroxide investigated. After storage in acidic solution at room temperature, many scars were formed by oxidative etching of HOPG and Pt-particle catalysts aggregated on the surface. In contrast, no surface change was observed without hydrogen peroxide. These results showed that hydrogen peroxide significantly deteriorates the Pt/HOPG electrode, and the active surface area of the Pt particles, which was determined by cyclic voltammetry, was reduced after immersion in the solution. The influence of applied potential was also investigated, and the deterioration of the electrode was accelerated at potentials both more positive and negative than open-circuit potential (ca. ). Moreover, similar degradation phenomenon was observed when the potential was set at , at which a large amount of is formed in oxygen reduction, in -saturated -free acid solution for .